Homemade wireless remote control intermediate frequency switcher circuit

This article introduces a radio-controlled satellite mid-frequency switcher that can control the switching work of four dual-polarized tuners (with some additional components, up to 10 dual-polarized tuners can be controlled), thus improving the performance of only a single 0 The digital satellite receiver with /22kHz or 0/12V control function cannot switch multiple tuners. The switcher has a simple circuit structure and few components, making it easy for amateur satellite TV enthusiasts to make their own. Working principle: The schematic diagram of the wireless intermediate frequency switch is shown in Figure 1. A1 is a dedicated transmitting module for radio remote control. When the touch switch S is pressed to turn on the power, its built-in transmitting antenna emits ultra-high frequency modulated electromagnetic waves with a frequency of 280MHz to 300MHz to the surrounding space, which is received by the dedicated receiving module A2 within an effective distance. The built-in receiving antenna receives, and after internal modulation, amplification, detection, and level conversion of the A2 module, a high-level pulse is output from the pin to turn on VT5 and control the action of the IC circuit. This IC is a decimal counting/timing decoder integrated circuit CD4017. At the moment of power-on, the circuit is automatically cleared, and the pin of the IC (Q0 terminal) outputs a high level, causing VT1 to conduct, relay J1 to pull in, and high frequency head LNB1 Work with electricity. With the input of pin (CK end) pulse, Q0~Q3 will take turns to output high level, correspondingly make J1~J4 take turns to pull in, thus controlling LNB1~LNB4 to take turns to conduct current. Component selection: The IC uses BCD counting/ten-segment decoding integrated circuit CD4017 or CC4017, etc. Its external pin functions are shown in Figure 2. The RCM-1A and RCM-1B used in conjunction with the wireless remote control special module consume less power. The measured static power consumption of the receiving circuit is only about 1mA; other types of radio remote control circuits can also be used instead. J1~J4 use ultra-small 12V DC relay JRC-21F, and the line package DC resistance is about 370Ω. VT1~VT5 use commonly used NPN low-power silicon transistors such as C1815, C8050, C9013, etc., requiring β>100, and use ∮0.51mm high-strength enameled wire on the N3mm ballpoint pen core Wind about 20 turns. R1~R7 all use RTX-1/8W carbon film resistors. There are no special requirements for the remaining components, and the parameters should be selected according to the values ​​marked on the diagram. The casing can be modified by removing the internal circuit board with a four-distributor, as shown in Figure 3. As long as the components selected for this circuit have good performance and the welding is correct, it can generally work normally without debugging. But please note: CD4017 is a CMOS circuit and is easily damaged by static electricity breakdown. Therefore, it is required that the soldering iron is well grounded or the plug is unplugged and soldered with residual heat. Figure 4 is a physical sample of an intermediate frequency switcher made by direct lap welding. If you need to make a 5-10 channel intermediate frequency switcher, just connect the CD4017 pin to the next output end of the corresponding control channel number (for example, when converting to a 5-way switcher, change the pin to pin Q5 terminal, and so on. If a 10-way switch is needed, the pin should be grounded), and then connect transistors, relays and other components to each output terminal.